If you want a Double Playfair challenge...
 Sunday, 05-Dec-1999 14:19:50 

      164.124.250.213 writes:

      If you don't mind an outsider joining the fun, here is a code for you to crack. (And I thought you all just coded cracks =)

      Same basic rules as Nova. Your secret agent is sending an encrypted message using Double Playfair system. They used "STOP"
      as a break and "MESSAGE ENDS" at the end. The most recent playfair square keywords include BLUE DIAMONDS, HARD LIKE
      ROCK, OF QUARTZ, CRYSTAL PALACE.

      KGRJQ WVQEP XEDQR CAGKT QMNDN HQVEY LNCLZ UMLWG
      XMSPU JATUP DTYSR CZSCF AGNNM VWMIJ XORCK XMGDP
      OZWYX KZXWZ AGWFW CWBNJ EHYGO FKXZK OIWWG OXPUK
      HBXDO HALWM GNUEU CAXFT CFOON GWMMT FHWKN IMVWV
      CXFRP KVZZF DZXLD LUCRG YNWWV HKZJZ MNKCK NCFXX
      XPJQC NMLLX DNVJU IEHKX ATIVS GDMBN RCRSB NPJHK
      PJUYK LDSWX KXANH MYHWB JMHEW MZAIS ZMNDR RZAAG
      XNZAN JOPMV SGOIR CKTMM FZXOS PRCNW DNGNP DJKHA
      ZUWVP IKZAS WVSQW KDPFG WWBWY GRIHM NGRRC FXRUC
      BOZPM BHCNV VNJBZ DSMYC WTOQG GMOEC DQNHR ZZFHU
      SPMBR RWZON EGTBG LXRWK ZNDHP QXLMZ RRONK XRNRC
      FTHBR CWOCZ IMLCV NOZWY RGZAR CEOTI PKDVF GMFWG
      WWGGC FJYNL BPHWW KZSEH MBLKG GGGMV XBWDN WWMUY 


******************************

Double Playfair allows double-letter pairs (n/t) (n/t)

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double letter
 Sunday, 05-Dec-1999 15:33:01 

      194.78.232.222 writes:

      Hi Dan,

      didn't checked it deeply yet, but as this is 'double'-playfair it seems possible to me that we have double letter pair (each letter
      come from a different square). 

      Will try to confirm this later.

      Respects,
      Laurent.

      PS : Per Jeff request I'll write another playfair crackme just for him (but of course everybody can work on it). Hope to post it in a few
      days :) 

      Laurent 

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Re:I am in/ hopefully i did this right
 Sunday, 05-Dec-1999 16:40:54 

      216.224.153.54 writes:

      I am really blind as a bat lately...
      to save u all time (if I did it right)

      here is the first step breakdown...not sure if I have put the message end correctly but tried to take my time and do the rest corrctly
      (don't trust me though)

      KRQVE XDRAK QNNQE LCZMW XSUAU DYRZC ANMWI XRKMD OWXZW AWWWN EYOKZ OWGXU HXOAW GUUAF CONWM FWNMW
      GJWQP EQCGT MDHVY NLULG MPJTP TSCSF GNVMJ OCXGP ZYKXZ GFCBJ HGFXK IWOPK BDHLM NECXT FOGMT HKIVV
      CFPVZ DXDUR YWVKJ MKKCX XJCML DVUEK AISDB RRBPH PUKDW KAHYW JHWZI ZNRZA XZNOM SORKM FXSRN DGPJH
      XRKZF ZLLCG NWHZZ NCNFX PQNLX NJIHX TVGMN CSNJK JYLSX XNMHB MEMAS MDRAG NAJPV GICTM ZOPCW NNDKA
      ZWPKA WSWDF WBYRH NRCXU BZMHN VJZSY WOGME DNRZH SMRWO ETGXW ZDPXM ROKRR FHRWC ILVOW RZRET PDFMW
      UVIZS VQKPG WWGIM GRFRC OPBCV NBDMC TQGOC QHZFU PBRZN GBLRK NHQLZ RNXNC TBCOZ MCNZY GACOI KVGFG
                      ? MESSA
                      G EENDS
      WGCJN BHWZE MLGGM XWNWU
      WGFYL PWKSH BKGGV BDWMY 




      jeff 

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I have problems wrapping my brain around this
 Sunday, 05-Dec-1999 23:11:11 

      207.230.57.235 writes:

      The breaking into 5s is just for transmission, the original break is arbitrary, right? And then after the first break it is fence railed
      before/during encryption?

      Sorry if I'm dense, but I can't even figure out how to get a grip on this one. Any help very appreciated.

      Dan 

*************************

Re: Re:I am in/ hopefully i did this right
 Monday, 06-Dec-1999 06:03:23 

      203.57.68.13 writes:

      Hi everyone hope you don't mind me butting in but I have a little more time this time and would like to join in when possible.

      Jeff I concur with your break down of the message so far. However, the message is only split into blocks of five for transmission
      purposes. This means that we do not know where the phrase "message ends" fits into the scheme of things.

      I post below my notes as I have them so far in the hope that they will help. I am a little stumped as to the next step at this point.

      Begin Notes
      **************************************
      Ok this is a different kettle of fish than playfair altogether. In fact they should have called this one Playunfair.

      It seems to me the first hurdle is to determine the size of the blocks that the original text is split into?

      So first delete all the spaces which divide it into blocks of five, these are just for the transmission and so are distracting to what we
      want to achieve.

      Now we have a long line of text. Now we need to split this with the first letter on the top line and the second letter on the bottom
      the third on the top the fourth on the bottom and so on. This in itself is no easy task but thanks to uedits column mode editing and
      find and replace it was made a lot easier. So we end up with:

      KRQVEXDRAKQNNQELCZMWXSUAUDYRZCANMWIXRKMDOWXZWAWWWNEYOKZOWGX
      GJWQPEQCGTMDHVYNLULGMPJTPTSCSFGNVMJOCXGPZYKXZGFCBJHGFXKIWOP

      UHXOAWGUUAFCONWMFWNMWCFPVZDXDURYWVKJMKKCXXJCMLDVUEKAISDBRRBP
      KBDHLMNECXTFOGMTHKIVVXRKZFZLLCGNWHZZNCNFXPQNLXNJIHXTVGMNCSNJ

      HPUKDWKAHYWJHWZIZNRZAXZNOMSORKMFXSRNDGPJHZWPKAWSWDFWBYRHNRCX
      KJYLSXXNMHBMEMASMDRAGNAJPVGICTMZOPCWNNDKAUVIZSVQKPGWWGIMGRFR

      UBZMHNVJZSYWOGMEDNRZHSMRWOETGXWZDPXMROKRRFHRWCILVOWRZRETPDFM
      COPBCVNBDMCTQGOCQHZFUPBRZNGBLRKNHQLZRNXNCTBCOZMCNZYGACOIKVGF

      WWGCJNBHWZEMLGGMXWNWU
      GWGFYLPWKSHBKGGVBDWMY

      Broken into blocks of 60 chars for ease of reading.

      So next we need to determine what we do know for sure. The only thing in this case that we can be sure of is that we have
      "MESSAGE ENDS" at the end. However this could be split into groups of an unknown number of characters. It could also be in the
      format "MESSAGE ENDS" or "MESSAGE ENDSX" depending on the offset of its position in the message.

      ******************************
      End Notes

      Whoa this scrambles your brain a little....


      Hope this comes out ok with the formatting it should read the same as Jeffs but without the blocks of five




      ShADδ 

**************************************

Could there be more than one X at end?
 Monday, 06-Dec-1999 06:22:53 

      207.230.57.220 writes:

      ala EEND or GEEND?
      SXXX SXXXX 

      Dan 

********************************

Don't think so ...
 Monday, 06-Dec-1999 06:51:16 

      194.78.234.250 writes:

      Hi Dan,

      I don't think there could be more than 1 X at the end. In nova double-playfair explanation they said 'divide the last block in egal
      length' (or something alike). So, 1 X would allow to round an odd number of final letters, but more X would not fit this rule.

      Don't know much more at this time. I'm writing a proggie to crypt and decrypt with double playfair rule in the hope that it will bring
      some light on this.

      Regards,

      Laurent. 
***********************************

Re: Don't think so ...
 Monday, 06-Dec-1999 15:35:15 

      216.58.8.51 writes:

      Greetings 

      I think the X would be appended at the end if the message is not even before encryption and that would make the cipher even.
      The trouble I have at the moment is determining the period.

      As I see it the period can be 5, 6, 8, 9, 10, 12, 13, 14, 16, 18, 20, 21, 22, 24, or 25 (assuming it is no longer than 25)
      But cannot be 7, 11, 15, 17, 19, or 23

      Princess 

*************************

Re: Re: Don't think so ...
 Monday, 06-Dec-1999 16:16:33 

      195.238.21.77 writes:

      Hi Princess,

      we are both violating seeker's rules (especially the one saying 'please open new thread'), but I'm sure he won't mind :)

      Can you explain how you eliminate 7 ,11, 15, ...

      I'm asking cause I don't find the same result as you :( See my post above for the method I used (beware, I made a mistake, the
      result posted are false, but the method is valid IMHO).

      I come up with the following 'valid' period : 5,7,8,10,13,15,16,17 (not checked above 19).


      Respects,
      Laurent 

************************

I messed up.
 Monday, 06-Dec-1999 17:36:10 

      216.58.8.130 writes:

      Hi Laurent

      Yes but I buggered up my notes. I started by dividing the whole cipher by two giving 260 then dividing by 7 giving a remainder of
      one which would be odd or not possible. I had intended to remember I had one for each pair of 7's which would then give length with
      7 as remainder two. But I messed up. Please disregard the above.

      Princess 

************************

No problem, princess :) .... I first made the same mistake :) (n/t) (Laurent)

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